Agricultural waste modified composite board and preparation method thereof

Abstract

The invention relates to the technical field of composite boards, in particular to an agricultural waste modified composite board and a preparation method thereof. According to the invention, an agricultural waste high-valued regeneration technology is innovatively adopted, and a four-dimensional functional structure design of the panel layer, the substrate layer, the weight reduction layer and the protection layer is adopted, so that a multi-component synergistic effect of biomass fiber interface enhancement, porous weight reduction structure optimization and nano protection system construction is realized; according to the composite board, the problems that a traditional artificial board is prone to deformation, not resistant to bacteria, poor in environmental tolerance and the like are solved, agricultural waste is successfully converted into a novel green building material with the potential of replacing a wood artificial board, and the composite board can be widely applied to special scenes such as indoor decoration, outdoor landscape engineering and high-temperature and high-humidity scenes and has remarkable ecological benefits.

Description

Technical Field

[0001] The invention relates to the technical field of composite boards, and in particular to an agricultural waste modified composite board and a preparation method thereof. Background Art

[0002] The resource utilization of agricultural waste has become an important practice area of ​​the global circular economy. In agricultural ecosystems, the difficulties in handling biomass by-products such as straw, rice husks, and bagasse reflect the problem of resource mismatch in the development of modern agriculture. According to statistics from the Food and Agriculture Organization of the United Nations, about 40% of agricultural residues in developing countries are still disposed of in primitive ways such as open-air burning. This extensive treatment not only aggravates greenhouse gas emissions, but also produces persistent organic pollutants that form cross-border environmental pollution through atmospheric circulation. Even in standardized disposal scenarios, soil acidification caused by landfills and methane escape during composting also restrict the sustainability of traditional treatment technologies. This dual loss of resources and environmental benefits is driving a wave of innovation in waste high-value utilization technologies. In the field of materials science, the research and development of agricultural waste-based panels has undergone a paradigm shift from simple substitution to functional design. In the current mainstream preparation technology system, the physical crushing-adhesive molding method is limited by the environmental defects of petrochemical-based adhesives, and its products are prone to formaldehyde slow release in a hot and humid environment, resulting in deterioration of indoor air quality; the biomass self-bonding method faces the process stability challenge brought by the fluctuation of raw material components, especially when dealing with waste with an unbalanced cellulose / lignin ratio, it is often necessary to supplement synthetic resins to maintain the interface bonding strength; and although the modified composite technology can improve the interface performance of the material, the salt-containing wastewater produced by chemical modification and the strict temperature control conditions required for biological enzymatic hydrolysis have significantly increased the threshold for industrial implementation. These technical bottlenecks have jointly made it difficult for existing products to break through the triangular constraints of performance-cost-environmental protection. The bending strength of traditional agricultural waste boards is much lower than that of wood particleboards and density boards. Unmodified boards are prone to moisture absorption, expansion, mildew, and have extremely poor weather resistance, which cannot meet the needs of outdoor use. Agricultural waste itself is flammable and flame retardants need to be added, but this will significantly increase costs and reduce mechanical properties. The synergistic effect of these defects seriously limits the application potential of materials in high-end scenarios such as green buildings and outdoor facilities. Therefore, based on the above problems, it is extremely necessary to develop a multifunctional flame-retardant, environmentally friendly and safe composite board using agricultural waste. Summary of the invention

[0003] In view of the defects of the prior art, the purpose of the present invention is to provide an agricultural waste modified composite board and a preparation method thereof. The present invention comprehensively improves the mechanical strength, durability, environmental protection performance and processing performance of the agricultural waste modified composite board through high-value utilization of agricultural waste, layered functional design and multi-component synergistic efficiency, which not only effectively solves the defects of easy hygroscopic expansion and extremely poor weather resistance of traditional boards, but also realizes high-value utilization of waste. It can effectively replace traditional wood-based panels and is suitable for interior decoration, outdoor construction and special scenes.

[0004] The technical effect of the present invention is achieved by the following technical solution: an agricultural waste modified composite board, which comprises, from top to bottom, a panel layer, a substrate layer, a weight-reducing layer and a protective layer; Preferably, the panel layer comprises the following components in parts by weight: 15-18 parts of ZnO@corncob porous carbon, 8-12 parts of magnesium oxide, 5-6 parts of magnesium sulfate, 1-1.2 parts of hydroxyethyl cellulose, 0.2-0.25 parts of silane coupling agent, 8-10 parts of sunflower disk carbon, 18-22 parts of isocyanate glue and 12-14 parts of light calcium carbonate, as well as one glass fiber cloth and one non-woven fiber cloth; Preferably, the substrate layer comprises the following components by weight: 10 to 15 parts of sunflower stem carbon fiber, 2 to 3 parts of nano-SiO 2 , 0.2-0.3 parts of silane coupling agent, 12-15 parts of hemp fiber, 6-8 parts of hollow glass microspheres, 0.4-0.5 parts of nano silver, 0.5-0.6 parts of hydroxyethyl cellulose and 15-20 parts of isocyanate glue, and two pieces of non-woven fiber cloth; Preferably, the composition of the weight-reducing layer includes the following components by weight: 15-20 parts of rice husk ash porous carbon, 8-12 parts of sunflower stem carbon powder, 12-15 parts of bio-modified asphalt, 0.3-0.5 parts of hydroxymethyl cellulose, 10-14 parts of chopped basalt fibers and 12-15 parts of water-based polyurethane glue, and a basalt fiber mesh; Preferably, the protective layer comprises the following components by weight: 8-12 parts of ZnO@corncob porous carbon, 4-6 parts of sunflower disk carbon, 8-12 parts of polyvinyl acetate emulsion, 12-15 parts of polyurethane acrylate, 0.3-0.5 parts of hydroxymethyl cellulose, 0.5-0.8 parts of KH-570 silane coupling agent, 15-20 parts of water-based acrylic resin and 2-3 parts of nano-SiO 2 , as well as one sheet of fiberglass cloth and one sheet of basalt fiber mesh; Preferably, the specific preparation steps of the ZnO@corncob porous carbon are as follows: S1: The agricultural waste corn cobs are completely immersed in deionized water for 24 hours, then immersed in a 5wt% NaOH solution for 2-3 hours, washed with water until neutral, dried at 80°C for 6-12 hours, crushed and screened through a 60-80 mesh sieve to obtain pretreated corn cobs; S2: adding the pretreated corn cob prepared in step S1 into a reaction furnace, heating to 600-900° C. at a rate of 5° C. / min under a nitrogen atmosphere, keeping the temperature for 1-2 hours, and then naturally cooling to room temperature to obtain a carbonized product; S3: the carbonized product in step S2 is mixed with 85wt% phosphoric acid, impregnated for 24h, then dried at 120°C for 3-6h, added to a reaction furnace, heated to 500-600°C at a rate of 5°C / min under a nitrogen atmosphere, kept warm for 1-1.5h, naturally cooled to room temperature, soaked in 5wt% sodium hydroxide solution for 2h, washed with deionized water until neutral, and dried at 105°C for 2-3h to obtain an activated product; S4: Immerse the activated product prepared in step S3 in a 0.3-0.5M zinc nitrate aqueous solution, vacuum impregnate for 30 minutes, stir at 200 rpm for 6 hours, dry at 80°C for 12-16 hours, add to a reactor, heat to 600-650°C at a rate of 5°C / min under a nitrogen atmosphere, keep warm for 12 hours, naturally cool to room temperature, ultrasonically treat, and dry at 105°C for 6-10 hours to obtain ZnO@corncob porous carbon; Preferably, in step S3, the ratio of the carbonization product to phosphoric acid is 1 g: 0.5-1 mL; Preferably, in step S4, the ratio of the amount of the activated product to the zinc nitrate aqueous solution is 1 g: 10-15 mL; the ultrasonic treatment parameters are 100-150 W, 40 kHz, and time 20-30 min; Preferably, the specific preparation steps of the bio-modified asphalt are as follows: S101: heating the asphalt to 160-170°C to obtain preheated asphalt; drying the lignin powder at 120°C for 2 hours to obtain pretreated lignin; mixing the preheated asphalt and the pretreated lignin, maintaining the temperature at 160-170°C, stirring and mixing at a speed of 5000-8000 rpm for 30 minutes, then adding KH-570 silane coupling agent, continuing to stir for 15-20 minutes, and standing at 150°C for 2 hours to obtain bio-modified asphalt; Preferably, in step S101, the mass ratio of the preheated asphalt to the pretreated lignin is 0.7-0.8:0.2-0.3; the amount of the KH-570 silane coupling agent is 1-2% of the amount of the substrate; Preferably, the sunflower disk carbon is prepared by subjecting the crushed disk to conventional acid pretreatment, carbonization and potassium hydroxide activation treatment; the rice husk ash porous carbon is prepared by conventional carbonization and potassium hydroxide activation treatment; Preferably, the specific preparation steps of the sunflower stem carbon fiber are as follows: S201: treating the sunflower stems at a pressure of 1.5-2MPa for 5-8min to separate cellulose and lignin to obtain loose fiber bundles; heating the loose cellulose to 1200°C at a rate of 10°C / min under a nitrogen atmosphere, keeping the temperature for 2-3h, naturally cooling to room temperature, washing with deionized water and ethanol three times, then soaking with 2wt% KH550 solution at 50-60°C for 1-2h, and drying at 80-100°C for 2h to obtain sunflower stem carbon fibers; Preferably, the KH-550 solution is prepared from KH-550 silane coupling agent and 90wt% ethanol solution; Preferably, the silane coupling agent in the panel layer and the substrate layer is any one of KH-550 silane coupling agent, KH560 silane coupling agent and KH792 silane coupling agent.

[0005] Preferably, another aspect of the present invention is to provide a method for preparing an agricultural waste modified composite board, and the specific preparation steps are as follows: S301: Add ZnO@corncob porous carbon, magnesium oxide, magnesium sulfate, sunflower disc carbon and light calcium carbonate into a mixer by weight, premix at 500rpm for 5-10min, then add hydroxyethyl cellulose and silane coupling agent, mix at 800rpm for 10-20min; add isocyanate glue, stir at 2000rpm for 20-30min to obtain panel layer slurry; evenly coat the prepared panel layer slurry on glass fiber cloth with a thickness of 3-5mm, then attach non-woven fiber cloth, place the mold in a hot press, hot press at 60℃ and 5MPa for 30min, and oven age at 60℃ for 24h to obtain the panel layer; S302: immersing hemp fiber in a 2wt% silane coupling agent solution, adjusting the pH to 5, drying for 30-50 min, and drying at 80°C for 2 h to obtain pretreated hemp fiber; adding nanosilver to one-half part by weight of isocyanate glue, ultrasonically treating, adding the remaining part by weight of isocyanate glue, stirring at 2000 rpm for 10 min, and obtaining a pretreated adhesive; adding nano-SiO 2, hollow glass microspheres and sunflower stem carbon fibers are added to a mixer, premixed at 400rpm for 10-20min, hydroxyethyl cellulose is added, and mixed at 600rpm for 15-30min; pretreated adhesive is added, stirred at 3000rpm for 30-50min, pretreated hemp fiber is added, and stirred at 500rpm for 5-10min to obtain substrate layer slurry; the substrate layer slurry is evenly applied to the non-woven fiber cloth with a thickness of 6-8mm, and covered with a second layer of non-woven fiber cloth, and the mold is placed in a hot press, pre-pressed at 2MPa for 5min, increased to 8MPa, heated to 120℃, maintained at pressure for 25min, and aged in an oven at 80℃ for 12h to obtain a base plate; S303: adding porous carbon from rice husk ash, carbon powder from sunflower stalks and chopped basalt fibers into a mixer, mixing at 500 rpm for 10 to 20 min, adding hydroxymethyl cellulose, stirring at 800 rpm for 15 to 30 min, adding bio-modified asphalt and water-based polyurethane adhesive, stirring at 2000 rpm for 25 to 40 min, and obtaining a weight-reducing layer coating; applying the weight-reducing layer coating evenly to the basalt fiber grid with a thickness of 8 to 10 mm, placing the mold in a hot press, maintaining the pressure at 3 MPa for 24 h, then reducing the pressure to 1 MPa, maintaining the pressure for 10 min, and standing for 2 to 3 h to obtain a weight-reducing layer; S304: Water-based acrylic resin, polyurethane acrylate, polyvinyl acetate emulsion and hydroxymethyl cellulose were added and mixed in sequence, and stirred at 2000 rpm for 15 to 20 minutes. Then, KH-570 silane coupling agent was added, and stirred at 3000 rpm for 20 to 30 minutes. ZnO@corncob porous carbon, sunflower disc carbon and nano-SiO 2 , stirring at 2000rpm for 30-50min to obtain a protective layer coating; applying the protective layer coating evenly to the glass fiber cloth with a thickness of 2-3mm, covering the basalt fiber grid, and after UV curing, heat curing at 80℃ for 2h under a pressure of 2MPa to obtain a protective layer; S305: stacking the prepared layers together, arranging them from bottom to top in the order of protective layer, weight reduction layer, substrate layer and panel layer, placing the stacked layers in a hot press, treating them at 80°C and 1MPa pressure for 5min, raising the temperature and pressure to 120°C and 8MPa for 30min, lowering the temperature and pressure to 100°C and 5MPa for 20min, lowering the pressure and temperature to 50°C and 2MPa for 30-60min, cooling to room temperature to obtain a formed composite sheet, cutting, grinding and surface treatment to obtain an agricultural waste modified composite sheet; Preferably, in step S302, the silane coupling agent solution is prepared from a silane coupling agent and a 90wt% ethanol solution; the ultrasonic treatment parameters are 100-150W, 40KHz, and time 10-20min; Preferably, in step S304, the UV curing parameters are 365nm and the radiation intensity is 100mW / cm 2 , time 5 to 10 minutes.

[0006] The beneficial effects of the present invention are as follows: The present invention utilizes multiple raw materials to achieve efficient synergistic effects of multiple components through a layered design. First, the present invention modifies corn carbon cores, uses phosphoric acid to penetrate the carbon skeleton, selectively etches disordered carbon regions, forms a microporous-mesoporous hierarchical pore structure, and improves specific surface area and adsorption capacity; during phosphoric acid activation, oxygen-containing functional groups such as carboxyl and hydroxyl groups are generated on the carbon surface, which enhance the chemical bonding ability with inorganic fillers (such as magnesium oxide) in the plate; the hierarchical pores provide adsorption-diffusion dual channels, and efficiently capture VOCs released by the plate; the surface functional groups form a covalent bond network with the adhesive to inhibit interface peeling, and then the zinc nitrate loading synergistically realizes functional directional modification. In the panel layer design, corn cob porous carbon is activated by phosphoric acid to form a hierarchical pore structure, and its surface carboxyl and hydroxyl functional groups are bonded with magnesium oxide through ionic bonds to synergistically improve the flame retardant performance; the loaded ZnO nanoparticles degrade the adsorbed formaldehyde and other pollutants through photocatalysis, forming an adsorption-purification self-cleaning mechanism. At the same time, the calcium-based ash of the sunflower disk carbon is catalytically carbonized at high temperature, and synergistically constructs a dense barrier layer with magnesium oxide to achieve a dual-channel fire barrier. In the substrate layer design, the rigid skeleton of silane-treated hemp fiber and sunflower stem carbon fiber forms a three-dimensional reinforced network; nano-silica fills the fiber gaps to effectively disperse local stress and avoid brittle fracture caused by stress concentration; the lightweight porous structure of the hollow glass microspheres forms a dynamic match with the elastic modulus of the isocyanate glue, absorbing energy through micropore collapse when external force impacts, and converting it into heat energy for release. In the design of the weight-reducing layer, a gradient transition is achieved through lightweighting. The viscoelasticity of bio-modified asphalt is combined with the rigidity of chopped basalt fibers to form a soft-hard alternating gradient structure, which not only buffers external impacts, but also constrains the deformation range through the fiber mesh. The mesopores of rice husk ash porous carbon and the micropores of sunflower stalk carbon powder form a through channel to achieve efficient dissipation of water and volatile substances and avoid stratification in a hot and humid environment. The final protective layer is weather-resistant and hydrophobic. The corn carbon pores store hydrophobic resin polyurethane acrylate to form a slow-release effect and maintain long-term hydrophobic properties. The ultraviolet shielding properties of ZnO delay resin aging and work together with the basalt fiber mesh to resist mechanical wear. The water-based acrylic resin forms a continuous film layer through cross-linking and curing, wrapping nano-silicon dioxide particles to form a micro-nano composite hydrophobic surface. The ultraviolet curing properties of polyurethane acrylate improve the surface hardness and wear resistance through light-induced cross-linking. The basalt fiber mesh is chemically bonded to the resin matrix through a silane coupling agent to form a composite interface of a rigid skeleton and a flexible coating to resist scratches and chemical corrosion.

[0007] In summary, the endothermic decomposition of magnesium salt in the panel layer and the carbonization barrier of carbon fiber in the substrate layer form a dual-stage flame retardant path of front-end inhibition and rear-end isolation: the panel layer quickly consumes heat and delays the temperature rise of the substrate layer; the continuous carbon layer of carbon fiber in the substrate layer blocks oxygen diffusion and forms global thermal protection. The glass fiber cloth in the panel layer bears the initial load through its high modulus characteristics, the fiber network in the substrate layer disperses stress through plastic deformation, and the flexible asphalt-fiber system in the weight-reducing layer further absorbs residual energy. This multi-level coordinated gradient design enables the board to maintain overall stability under complex loads. The hydrophobic surface of the protective layer can reduce water penetration, and the porous carbon in the panel layer absorbs water molecules and guides the water to escape through the open pores of the weight-reducing layer through capillary action, forming an anti-repellent and anti-humidity integrated humidity control mechanism. The nanosilver in the substrate layer destroys the microbial cell membrane by releasing silver ions, and the zinc oxide in the panel layer produces reactive oxygen species (ROS) through photocatalysis to inhibit the germination of mold spores; the hydrophobic surface of the protective layer reduces the adhesion of stains, and the three together construct a hygienic barrier of antibacterial, anti-mildew and anti-fouling. In addition, after the porous carbon of the panel layer absorbs pollutants such as formaldehyde, it is catalytically degraded into harmless substances under light through the loaded zinc oxide; the nano-silicon dioxide of the protective layer captures degradation byproducts through surface hydroxyl groups to prevent secondary release. The present invention uses carbonization and fiberization of agricultural waste (corn cobs, rice husks, sunflowers) to give the material natural porosity and biocompatibility; bio-based adhesives and modified asphalt replace petrochemical raw materials to reduce carbon emissions throughout the life cycle; waste panels can be recycled through controlled pyrolysis to form a closed cycle of environmentally friendly regeneration. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0009] Figure 1 is a schematic structural diagram of a composite plate prepared in Example 2 of the present invention; Figure 2 It is a graph showing the wear resistance test results of the composite plate samples prepared in Example 2 of the present invention and Comparative Examples 1 and 4; Figure 3 1 is a graph showing the antibacterial test results of the composite board samples prepared in Example 2 of the present invention and Comparative Examples 1, 2, and 4; Figure 4 is a SEM scanning electron microscope image of ZnO@corncob porous carbon prepared in Example 2 of the present invention; Explanation of reference numerals: 1. Panel layer; 2. Substrate layer; 3. Weight reduction layer; 4. Protective layer. DETAILED DESCRIPTION

[0010] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the raw materials involved in the present invention are purchased through conventional commercial channels.

[0011] Embodiment 1: An agricultural waste modified composite board, which comprises, from top to bottom, a panel layer 1, a substrate layer 2, a weight-reducing layer 3 and a protective layer 4; The panel layer 1 comprises the following components by weight: 15 parts of ZnO@corncob porous carbon, 8 parts of magnesium oxide, 5 parts of magnesium sulfate, 1 part of hydroxyethyl cellulose, 0.2 parts of silane coupling agent, 8 parts of sunflower disk carbon, 18 parts of isocyanate glue and 12 parts of light calcium carbonate, as well as one glass fiber cloth and one non-woven fiber cloth; The composition of the substrate layer 2 includes the following components by weight: 10 parts of sunflower stem carbon fiber, 2 parts of nano-SiO 2 , 0.2 parts of silane coupling agent, 12 parts of hemp fiber, 6 parts of hollow glass microspheres, 0.4 parts of nanosilver, 0.5 parts of hydroxyethyl cellulose and 15 parts of isocyanate glue, and two pieces of non-woven fiber cloth; The composition of the weight-reducing layer 3 includes the following components in parts by weight: 15 parts of rice husk ash porous carbon, 8 parts of sunflower stem carbon powder, 12 parts of bio-modified asphalt, 0.3 parts of hydroxymethyl cellulose, 10 parts of short-cut basalt fibers and 12 parts of water-based polyurethane glue, and one basalt fiber mesh; The protective layer 4 is composed of the following components by weight: 8 parts of ZnO@corncob porous carbon, 4 parts of sunflower disk carbon, 8 parts of polyvinyl acetate emulsion, 12 parts of polyurethane acrylate, 0.3 parts of hydroxymethyl cellulose, 0.5 parts of KH-570 silane coupling agent, 15 parts of water-based acrylic resin and 2 parts of nano-SiO 2 , as well as one sheet of fiberglass cloth and one sheet of basalt fiber mesh; The specific preparation steps of ZnO@corncob porous carbon are as follows: S1: 100 g of agricultural waste corn cobs were completely soaked in deionized water for 24 h, then soaked in 5 wt% NaOH solution for 2 h, washed with water until neutral, dried at 80 °C for 6 h, crushed and screened through a 60-mesh sieve to obtain pretreated corn cobs; S2: adding 100 g of the pretreated corn cob prepared in step S1 into a reaction furnace, heating to 600° C. at a rate of 5° C. / min under a nitrogen atmosphere, keeping the temperature for 2 h, and then naturally cooling to room temperature to obtain a carbonized product; S3: 100 g of the carbonized product prepared in step S2 was mixed with 50 mL of 85 wt% phosphoric acid, and the mixture was immersed in water for 24 h, and then dried at 120 °C for 3 h. The mixture was added to a reactor, and heated to 500 °C at a rate of 5 °C / min under a nitrogen atmosphere, and kept warm for 1.5 h. The mixture was naturally cooled to room temperature, immersed in a 5 wt% sodium hydroxide solution for 2 h, and washed with deionized water until neutral. The mixture was dried at 105 °C for 2 h to obtain an activated product. S4: 100 g of the activated product prepared in step S3 was immersed in 100 mL of 0.3 M zinc nitrate aqueous solution, vacuum impregnated for 30 min, stirred at 200 rpm for 6 h, dried at 80 ° C for 12 h, added to a reactor, heated to 600 ° C at a rate of 5 ° C / min under a nitrogen atmosphere, kept warm for 12 h, naturally cooled to room temperature, ultrasonically treated at 100 W, 40 kHz, time for 20 min, and dried at 105 ° C for 6 h to obtain ZnO@corncob porous carbon; The specific preparation steps of bio-modified asphalt are as follows: S101: 70g of asphalt was heated to 160°C to obtain preheated asphalt; 30g of lignin powder was dried at 120°C for 2h to obtain pretreated lignin; 70g of preheated asphalt and 30g of pretreated lignin were mixed, the temperature was maintained at 160°C, and the mixture was stirred at 5000rpm for 30min, then 1mL of KH-570 silane coupling agent was added, the mixture was stirred for 15min, and the mixture was allowed to stand at 150°C for 2h to obtain bio-modified asphalt; The sunflower disk carbon is prepared by subjecting the crushed disk to conventional acid washing pretreatment, carbonization and potassium hydroxide activation treatment; The porous carbon from rice husk ash was prepared by conventional carbonization and potassium hydroxide activation treatment. The specific preparation steps of sunflower stem carbon fiber are as follows: S201: The sunflower stems were treated at a pressure of 1.5 MPa for 8 min to separate cellulose and lignin to obtain loose fiber bundles; the loose cellulose was heated to 1200°C at a rate of 10°C / min under a nitrogen atmosphere, kept warm for 2 h, naturally cooled to room temperature, washed three times with deionized water and ethanol, and then soaked in 2wt% KH-550 solution at 50°C for 2 h, and dried at 80°C for 2 h to obtain sunflower stem carbon fibers; The specific preparation steps of agricultural waste modified composite panels are as follows: S301: Add ZnO@corncob porous carbon, magnesium oxide, magnesium sulfate, sunflower disc carbon and light calcium carbonate into a mixer by weight, premix at 500rpm for 5min, then add hydroxyethyl cellulose and KH-550 silane coupling agent, mix at 800rpm for 10min; add isocyanate glue, stir at 2000rpm for 20min to obtain panel layer slurry; evenly coat the prepared panel layer slurry on glass fiber cloth with a thickness of 3mm, then attach non-woven fiber cloth, place the mold in a hot press, hot press at 60℃ and 5MPa for 30min, and oven age at 60℃ for 24h to obtain panel layer 1; S302: immersing hemp fiber in a 2wt% KH-550 silane coupling agent solution, adjusting the pH to 5, drying for 30 min, and drying at 80°C for 2 h to obtain pretreated hemp fiber; adding nanosilver to one-half part by weight of isocyanate glue, ultrasonically treating at 100W, 40KHz, for 10 min, then adding the remaining part by weight of isocyanate glue, stirring at 2000rpm for 10 min, and obtaining a pretreated adhesive; adding nano-SiO 2 , hollow glass microspheres and sunflower stem carbon fibers were added into a mixer, premixed at 400rpm for 10min, hydroxyethyl cellulose was added and mixed at 600rpm for 15min, pretreated adhesive was added and stirred at 3000rpm for 30min, pretreated hemp fiber was added and stirred at 500rpm for 5min to obtain substrate layer slurry; the substrate layer slurry was evenly applied to the non-woven fiber cloth with a thickness of 6mm, and covered with a second layer of non-woven fiber cloth, the mold was placed in a hot press, pre-pressed at 2MPa for 5min, the pressure was increased to 8MPa, the temperature was increased to 120℃, the pressure was maintained for 25min, and the substrate was aged in an oven at 80℃ for 12h to obtain base plate 2; S303: Add rice husk ash porous carbon, sunflower stem carbon powder and chopped basalt fiber into a mixer, mix at 500rpm for 10min, add hydroxymethyl cellulose, stir at 800rpm for 15min, add bio-modified asphalt and water-based polyurethane adhesive, stir at 2000rpm for 25min, and obtain a weight-reducing layer coating; apply the weight-reducing layer coating evenly to the basalt fiber grid with a thickness of 8mm, place the mold in a hot press, maintain the pressure at 3MPa for 24h, then reduce it to 1MPa, maintain it for 10min, and let it stand for 2h to obtain a weight-reducing layer 3; S304: Water-based acrylic resin, polyurethane acrylate, polyvinyl acetate emulsion and hydroxymethyl cellulose were added and mixed in sequence, and stirred at 2000 rpm for 15 min. Then, KH-570 silane coupling agent was added and stirred at 3000 rpm for 20 min. ZnO@corncob porous carbon, sunflower disc carbon and nano-SiO 2, stirring at 2000rpm for 30min to obtain a protective layer coating; the protective layer coating was evenly applied to the glass fiber cloth with a thickness of 2mm, covering the basalt fiber grid, the UV curing parameters were 365nm, and the radiation intensity was 100mW / cm 2 After curing, the protective layer 4 was obtained by heat curing at 80°C for 2h under a pressure of 2MPa for 5min. S305: Stack the above-prepared layers together and arrange them in the order of protective layer 1, weight reduction layer 2, substrate layer 3 and panel layer 4 from bottom to top, put the stacked layers into a hot press, treat at 80°C and 1MPa pressure for 5min, increase the temperature and pressure to 120°C and 8MPa, treat for 30min, reduce the temperature and pressure to 100°C and 5MPa, treat for 20min, reduce the pressure and temperature to 50°C and 2Mpa, treat for 30min, cool to room temperature to obtain the formed composite board, cut, polish and surface treat to obtain the agricultural waste modified composite board.

[0012] Embodiment 2: An agricultural waste modified composite board, which comprises, from top to bottom, a panel layer 1, a substrate layer 2, a weight-reducing layer 3 and a protective layer 4; The panel layer 1 comprises the following components by weight: 18 parts of ZnO@corncob porous carbon, 12 parts of magnesium oxide, 6 parts of magnesium sulfate, 1.2 parts of hydroxyethyl cellulose, 0.22 parts of silane coupling agent, 10 parts of sunflower disk carbon, 20 parts of isocyanate glue and 14 parts of light calcium carbonate, as well as one glass fiber cloth and one non-woven fiber cloth; The composition of the substrate layer 2 includes the following components by weight: 15 parts of sunflower stem carbon fiber, 3 parts of nano-SiO 2 , 0.3 parts of silane coupling agent, 15 parts of hemp fiber, 8 parts of hollow glass microspheres, 0.5 parts of nano silver, 0.6 parts of hydroxyethyl cellulose and 20 parts of isocyanate glue, and two pieces of non-woven fiber cloth; The composition of the weight-reducing layer 3 includes the following components in parts by weight: 20 parts of rice husk ash porous carbon, 12 parts of sunflower stem carbon powder, 15 parts of bio-modified asphalt, 0.5 parts of hydroxymethyl cellulose, 14 parts of short-cut basalt fibers and 15 parts of water-based polyurethane glue, and a basalt fiber mesh; The protective layer 4 is composed of the following components by weight: 12 parts of ZnO@corncob porous carbon, 6 parts of sunflower disk carbon, 12 parts of polyvinyl acetate emulsion, 15 parts of polyurethane acrylate, 0.5 parts of hydroxymethyl cellulose, 0.8 parts of KH-570 silane coupling agent, 20 parts of water-based acrylic resin and 3 parts of nano-SiO 2 , as well as one sheet of fiberglass cloth and one sheet of basalt fiber mesh; The specific preparation steps of ZnO@corncob porous carbon are as follows: S1: 100 g of agricultural waste corn cobs were completely soaked in deionized water for 24 h, then soaked in 5 wt% NaOH solution for 3 h, washed with water until neutral, dried at 80 °C for 12 h, crushed and screened through an 80-mesh sieve to obtain pretreated corn cobs; S2: adding 100 g of the pretreated corn cob prepared in step S1 into a reaction furnace, heating to 900° C. at a rate of 5° C. / min under a nitrogen atmosphere, keeping the temperature for 1 h, and then naturally cooling to room temperature to obtain a carbonized product; S3: 100 g of the carbonized product prepared in step S2 was mixed with 100 mL of 85 wt% phosphoric acid, and the mixture was immersed in water for 24 h, and then dried at 120 ° C for 6 h, added to a reactor, heated to 600 ° C at a rate of 5 ° C / min under a nitrogen atmosphere, and kept warm for 1 h, naturally cooled to room temperature, immersed in 5 wt% sodium hydroxide solution for 2 h, washed with deionized water until neutral, and dried at 105 ° C for 3 h to obtain an activated product; S4: immerse 100g of the activated product prepared in step S3 in 150mL of 0.5M zinc nitrate aqueous solution, vacuum impregnate for 30min, stir at 200rpm for 6h, dry at 80℃ for 16h, add to the reactor, heat to 650℃ at a rate of 5℃ / min under nitrogen atmosphere, keep warm for 12h, cool naturally to room temperature, ultrasonically treat at 150W, 40kHz, time for 30min, and dry at 105℃ for 10h to obtain ZnO@corncob porous carbon; The specific preparation steps of bio-modified asphalt are as follows: S101: 75g of asphalt was heated to 170°C to obtain preheated asphalt; 25g of lignin powder was dried at 120°C for 2h to obtain pretreated lignin; 75g of preheated asphalt and 25g of pretreated lignin were mixed, the temperature was maintained at 170°C, and the mixture was stirred at 8000rpm for 30min, then 2mL of KH-570 silane coupling agent was added, the mixture was stirred for 20min, and the mixture was allowed to stand at 150°C for 2h to obtain bio-modified asphalt; The sunflower disk carbon is prepared by subjecting the crushed disk to conventional acid pretreatment, carbonization and potassium hydroxide activation treatment; the rice husk ash porous carbon is prepared by conventional carbonization and potassium hydroxide activation treatment; The specific preparation steps of sunflower stem carbon fiber are as follows: S201: The sunflower stems were treated at a pressure of 2MPa for 5min to separate cellulose and lignin to obtain loose fiber bundles; the loose cellulose was heated to 1200°C at a rate of 10°C / min under a nitrogen atmosphere, kept warm for 3h, naturally cooled to room temperature, washed three times with deionized water and ethanol, and then soaked in 2wt% KH-550 solution at 60°C for 1h, and dried at 100°C for 2h to obtain sunflower stem carbon fibers; The specific preparation steps of agricultural waste modified composite panels are as follows: S301: Add ZnO@corncob porous carbon, magnesium oxide, magnesium sulfate, sunflower disc carbon and light calcium carbonate into a mixer by weight, premix at 500rpm for 10min, then add hydroxyethyl cellulose and KH-550 silane coupling agent, mix at 800rpm for 20min; add isocyanate glue, stir at 2000rpm for 30min to obtain panel layer slurry; evenly coat the prepared panel layer slurry on glass fiber cloth with a thickness of 5mm, then attach non-woven fiber cloth, place the mold in a hot press, hot press at 60℃ and 5MPa for 30min, and oven age at 60℃ for 24h to obtain panel layer 1; S302: immersing hemp fiber in a 2wt% KH-550 silane coupling agent solution, adjusting the pH to 5, drying for 50 min, and drying at 80°C for 2 h to obtain pretreated hemp fiber; adding nanosilver to one-half part by weight of isocyanate glue, ultrasonically treating at 150W, 40KHz, for 20 min, and then adding the remaining part by weight of isocyanate glue, stirring at 2000rpm for 10 min to obtain a pretreated adhesive; adding nano-SiO 2 , hollow glass microspheres and sunflower stem carbon fibers were added into a mixer, premixed at 400rpm for 20min, hydroxyethyl cellulose was added and mixed at 600rpm for 30min, pretreated adhesive was added and stirred at 3000rpm for 50min, pretreated hemp fiber was added and stirred at 500rpm for 10min to obtain substrate layer slurry; the substrate layer slurry was evenly applied to the non-woven fiber cloth with a thickness of 8mm, and covered with a second layer of non-woven fiber cloth, the mold was placed in a hot press, pre-pressed at 2MPa for 5min, the pressure was increased to 8MPa, the temperature was increased to 120℃, the pressure was maintained for 25min, and the substrate was aged in an oven at 80℃ for 12h to obtain base plate 2; S303: Add rice husk ash porous carbon, sunflower stem carbon powder and chopped basalt fiber into a mixer, mix at 500rpm for 20min, add hydroxymethyl cellulose, stir at 800rpm for 30min, add bio-modified asphalt and water-based polyurethane adhesive, stir at 2000rpm for 40min, and obtain a weight-reducing layer coating; evenly apply the weight-reducing layer coating to the basalt fiber grid with a thickness of 10mm, place the mold in a hot press, maintain the pressure at 3MPa for 24h, then reduce to 1MPa, maintain for 10min, and let stand for 3h to obtain a weight-reducing layer 3; S304: Water-based acrylic resin, polyurethane acrylate, polyvinyl acetate emulsion and hydroxymethyl cellulose were added and mixed in sequence, and stirred at 2000 rpm for 20 min. Then, KH-570 silane coupling agent was added and stirred at 3000 rpm for 30 min. ZnO@corncob porous carbon, sunflower disc carbon and nano-SiO 2 , stirring at 2000rpm for 50min to obtain a protective layer coating; the protective layer coating was evenly applied to the glass fiber cloth with a thickness of 3mm, covering the basalt fiber grid, and the UV curing parameters were 365nm and the radiation intensity was 100mW / cm 2 After the curing is completed, the protective layer 4 is obtained by heat curing at 80°C for 2 hours under a pressure of 2 MPa. S305: Stack the above-prepared layers together and arrange them in the order of protective layer 1, weight reduction layer 2, substrate layer 3 and panel layer 4 from bottom to top, put the stacked layers into a hot press, treat at 80°C and 1MPa pressure for 5min, increase the temperature and pressure to 120°C and 8MPa, treat for 30min, reduce the temperature and pressure to 100°C and 5MPa, treat for 20min, reduce the pressure and temperature to 50°C and 2Mpa, treat for 60min, cool to room temperature to obtain the formed composite board, cut, polish and surface treat to obtain the agricultural waste modified composite board.

[0013] Embodiment 3: An agricultural waste modified composite board, which comprises, from top to bottom, a panel layer 1, a substrate layer 2, a weight-reducing layer 3 and a protective layer 4; The panel layer 1 comprises the following components by weight: 16 parts of ZnO@corncob porous carbon, 10 parts of magnesium oxide, 5.5 parts of magnesium sulfate, 1.1 parts of hydroxyethyl cellulose, 0.25 parts of silane coupling agent, 9 parts of sunflower disk carbon, 22 parts of isocyanate glue and 13 parts of light calcium carbonate, as well as one glass fiber cloth and one non-woven fiber cloth; The composition of the substrate layer 2 includes the following components by weight: 14 parts of sunflower stem carbon fiber, 2.5 parts of nano-SiO 2, 0.25 parts of silane coupling agent, 14 parts of hemp fiber, 7 parts of hollow glass microspheres, 0.45 parts of nano silver, 0.55 parts of hydroxyethyl cellulose and 18 parts of isocyanate glue, and two pieces of non-woven fiber cloth; The composition of the weight-reducing layer 3 includes the following components in parts by weight: 18 parts of rice husk ash porous carbon, 10 parts of sunflower stem carbon powder, 14 parts of bio-modified asphalt, 0.4 parts of hydroxymethyl cellulose, 12 parts of short-cut basalt fibers and 14 parts of water-based polyurethane glue, and a basalt fiber mesh; The protective layer 4 is composed of the following components by weight: 10 parts of ZnO@corncob porous carbon, 5 parts of sunflower disk carbon, 10 parts of polyvinyl acetate emulsion, 13 parts of polyurethane acrylate, 0.4 parts of hydroxymethyl cellulose, 0.7 parts of KH-570 silane coupling agent, 18 parts of water-based acrylic resin and 2.5 parts of nano-SiO 2 , as well as one sheet of fiberglass cloth and one sheet of basalt fiber mesh; The specific preparation steps of ZnO@corncob porous carbon are as follows: S1: 100 g of agricultural waste corn cobs were completely soaked in deionized water for 24 h, then soaked in 5 wt% NaOH solution for 2.5 h, washed with water until neutral, dried at 80 °C for 10 h, crushed and screened through a 70-mesh sieve to obtain pretreated corn cobs; S2: Add 100 g of the pretreated corn cob prepared in step S1 into a reactor, heat it to 800° C. at a rate of 5° C. / min under a nitrogen atmosphere, keep it warm for 1.5 h, and then naturally cool it to room temperature to obtain a carbonized product; S3: 100 g of the carbonized product prepared in step S2 was mixed with 80 mL of 85 wt% phosphoric acid, and the mixture was immersed in water for 24 h, and then dried at 120 ° C for 5 h, added to a reactor, heated to 550 ° C at a rate of 5 ° C / min under a nitrogen atmosphere, and kept warm for 1.2 h. The mixture was naturally cooled to room temperature, immersed in a 5 wt% sodium hydroxide solution for 2 h, washed with deionized water until neutral, and dried at 105 ° C for 2.5 h to obtain an activated product; S4: 100 g of the activated product prepared in step S3 was immersed in 130 mL of 0.4 M zinc nitrate aqueous solution, vacuum impregnated for 30 min, stirred at 200 rpm for 6 h, dried at 80 ° C for 15 h, added to a reactor, heated to 620 ° C at a rate of 5 ° C / min under a nitrogen atmosphere, kept warm for 12 h, naturally cooled to room temperature, ultrasonically treated at 120 W, 40 kHz, time for 25 min, and dried at 105 ° C for 8 h to obtain ZnO@corncob porous carbon; The specific preparation steps of bio-modified asphalt are as follows: S101: 80g of asphalt was heated to 165°C to obtain preheated asphalt; 20g of lignin powder was dried at 120°C for 2h to obtain pretreated lignin; 80g of preheated asphalt and 20g of pretreated lignin were mixed, the temperature was maintained at 165°C, and the mixture was stirred at 7000rpm for 30min, then 1.5mL of KH-570 silane coupling agent was added, the mixture was stirred for 18min, and the mixture was allowed to stand at 150°C for 2h to obtain bio-modified asphalt; The sunflower disk carbon is prepared by subjecting the crushed disk to conventional acid pretreatment, carbonization and potassium hydroxide activation treatment; the rice husk ash porous carbon is prepared by conventional carbonization and potassium hydroxide activation treatment; The specific preparation steps of sunflower stem carbon fiber are as follows: S201: The sunflower stems were treated at a pressure of 1.8 MPa for 7 minutes to separate cellulose and lignin to obtain loose fiber bundles; the loose cellulose was heated to 1200°C at a rate of 10°C / min under a nitrogen atmosphere, kept warm for 2.5 hours, naturally cooled to room temperature, washed with deionized water and ethanol three times, and then soaked in 2wt% KH-550 solution at 55°C for 1.5 hours, and dried at 90°C for 2 hours to obtain sunflower stem carbon fibers; The specific preparation steps of agricultural waste modified composite panels are as follows: S301: Add ZnO@corncob porous carbon, magnesium oxide, magnesium sulfate, sunflower disc carbon and light calcium carbonate into a mixer by weight, premix at 500rpm for 8min, then add hydroxyethyl cellulose and KH-560 silane coupling agent, mix at 800rpm for 15min; add isocyanate glue, stir at 2000rpm for 25min to obtain panel layer slurry; evenly coat the prepared panel layer slurry on glass fiber cloth with a thickness of 4mm, then attach non-woven fiber cloth, place the mold in a hot press, hot press at 60℃ and 5MPa for 30min, and oven age at 60℃ for 24h to obtain panel layer 1; S302: immersing hemp fiber in a 2wt% KH-560 silane coupling agent solution, adjusting the pH to 5, drying for 40 min, and drying at 80°C for 2 h to obtain pretreated hemp fiber; adding nanosilver to one-half part by weight of isocyanate glue, ultrasonically treating at 120W, 40KHz, for 15 min, and then adding the remaining part by weight of isocyanate glue, stirring at 2000rpm for 10 min to obtain a pretreated adhesive; adding nano-SiO 2, hollow glass microspheres and sunflower stem carbon fibers were added into a mixer, premixed at 400rpm for 15min, hydroxyethyl cellulose was added and mixed at 600rpm for 25min, pretreated adhesive was added and stirred at 3000rpm for 40min, pretreated hemp fiber was added and stirred at 500rpm for 8min to obtain substrate layer slurry; the substrate layer slurry was evenly applied to the non-woven fiber cloth with a thickness of 7mm, and covered with a second layer of non-woven fiber cloth, the mold was placed in a hot press, pre-pressed at 2MPa for 5min, the pressure was increased to 8MPa, the temperature was increased to 120℃, the pressure was maintained for 25min, and the substrate was aged in an oven at 80℃ for 12h to obtain base plate 2; S303: Add rice husk ash porous carbon, sunflower stem carbon powder and chopped basalt fiber into a mixer, mix at 500rpm for 15min, add hydroxymethyl cellulose, stir at 800rpm for 25min, add bio-modified asphalt and water-based polyurethane adhesive, stir at 2000rpm for 35min, and obtain a weight-reducing layer coating; evenly apply the weight-reducing layer coating to the basalt fiber grid with a thickness of 9mm, place the mold in a hot press, maintain the pressure at 3MPa for 24h, then reduce to 1MPa, maintain for 10min, and let stand for 2.5h to obtain a weight-reducing layer 3; S304: Water-based acrylic resin, polyurethane acrylate, polyvinyl acetate emulsion and hydroxymethyl cellulose were added and mixed in sequence, and stirred at 2000 rpm for 18 min. Then, KH-570 silane coupling agent was added and stirred at 3000 rpm for 25 min. ZnO@corncob porous carbon, sunflower disc carbon and nano-SiO 2 , stirring at 2000rpm for 40min to obtain a protective layer coating; the protective layer coating was evenly applied to the glass fiber cloth with a thickness of 3mm, covering the basalt fiber grid, the UV curing parameter was 365nm, and the radiation intensity was 100mW / cm 2 After the curing is completed, the protective layer 4 is obtained by heat curing at 80°C for 2 hours under a pressure of 2 MPa. S305: Stack the above-prepared layers together and arrange them in the order of protective layer 1, weight reduction layer 2, substrate layer 3 and panel layer 4 from bottom to top, put the stacked layers into a hot press, treat at 80°C and 1MPa pressure for 5min, increase the temperature and pressure to 120°C and 8MPa, treat for 30min, reduce the temperature and pressure to 100°C and 5MPa, treat for 20min, reduce the pressure and temperature to 50°C and 2Mpa, treat for 50min, cool to room temperature to obtain the formed composite board, cut, polish and surface treat to obtain the agricultural waste modified composite board.

[0014] Comparative Example 1: The operation of Comparative Example 1 is basically the same as that of Example 2. The only difference between Comparative Example 1 and Example 2 is that the panel layer and the protective layer in Comparative Example 1 use ordinary corncob porous carbon instead of ZnO@corncob porous carbon.

[0015] Comparative Example 2: The operation of Comparative Example 2 is basically the same as that of Example 2. The only difference between Comparative Example 2 and Example 2 is that asphalt is used in the weight-reducing layer in Comparative Example 2 to replace lignin bio-modified asphalt, and nano-silver is removed.

[0016] Comparative Example 3: The operation of Comparative Example 3 is substantially the same as that of Example 2, and the only difference between Comparative Example 3 and Example 2 is that the weight-reducing layer in Comparative Example 3 does not use silane to treat the hemp fiber.

[0017] Comparative Example 4: The operation of Comparative Example 4 is basically the same as that of Example 2. The only difference between Comparative Example 4 and Example 2 is that the protective layer in Comparative Example 4 uses KH550 silane coupling agent instead of KH570 silane coupling agent.

[0018] Performance Test: Mechanical strength and weather resistance test: The tensile strength and flexural strength tests were performed on the composite sheet samples prepared in Examples 1 to 3 and Comparative Examples 1 to 4 using a universal material testing machine. The tensile strength was tested in accordance with GB / T 1040.1-2018; the flexural strength was tested in accordance with GB / T 9341-2008; the impact strength was measured by a plastic pendulum impact tester in accordance with GB / T 1843-2008, and the weather resistance was tested in accordance with standard GB / T 2423.3. The composite sheet samples prepared in Example 2 and Comparative Examples 1 to 4 were observed. The composite sheet samples were tested at 60°C and 75% humidity for 2000h, and the appearance was observed for cracking and blistering at 1000h and 2000h, respectively. The tensile strength, flexural strength, impact strength and weather resistance test results are shown in Table 1 below.

[0019] Table 1. Mechanical strength and weather resistance test results of composite panels

[0020] It can be seen from the results in Table 1 that the composite board prepared by the present invention using agricultural waste has excellent mechanical strength and weather resistance, and realizes efficient mechanical strength improvement through the synergistic effect of multi-level and multi-raw materials; it can be seen from the results of Comparative Example 1 and Example 2 that the modulus of ordinary corn cob carbon is significantly lower than that of ZnO@corn cob carbon, and ordinary carbon lacks carboxyl / hydroxyl functional groups, and the ionic bond binding force with magnesium oxide is reduced, resulting in reduced rigidity of the panel layer, but the glass fiber cloth still dominates the tensile properties; it can be seen from the results of Comparative Example 2 and Example 2 that the elastic modulus of petroleum asphalt is lower than that of lignin bio-modified asphalt, basalt grid and chopped fibers still provide the main impact resistance, the mechanical strength is reduced to a certain extent, the softening point of petroleum asphalt is low, creep will occur at 60°C, and the reduction The deformation of the heavy layer causes blistering; and without nano-silver antibacterial, the growth of microorganisms may accelerate the hydrolysis of the resin, resulting in a significant decrease in weather resistance; from the results of Comparative Example 3 and Example 2, it can be seen that the unsilane-treated hemp fiber is only physically bonded, the substrate layer becomes a stress concentration point, and the tensile strength and impact strength drop sharply. In addition, the untreated hemp fiber has a significant water absorption rate, and the expansion stress of the substrate layer may cause through-cracks, fiber-resin debonding, and further lead to significant interlayer peeling; from the results of Comparative Example 4 and Example 2, it can be seen that the amino group of KH-550 only forms hydrogen bonds with the resin, and the interfacial bonding force is significantly affected. The amino group of KH-550 may coordinate with nano-silver to cause agglomeration, which may lead to a decrease in the stress dispersion ability of the substrate layer, thereby reducing the bending strength.

[0021] Wear resistance test: The composite sheet samples prepared in Example 2 and Comparative Examples 1 and 4 were cut into 100×100 mm test pieces and subjected to friction and wear tests. The load was 1 kg, the CS-10 grinding wheel was used, and the test was performed for 500 revolutions. The mass loss and wear scar depth were recorded. The results are shown in FIG. Figure 2 shown.

[0022] Depend on Figure 2 The results show that the composite board prepared by the present invention has excellent wear resistance. From the results of Comparative Example 1 and Example 2, it can be seen that the hardness of ordinary corncob carbon is much lower than that of ZnO@corncob carbon, and the lack of hard fillers may lead to a significant increase in the wear scar depth. From the results of Comparative Example 4 and Example 2, it can be seen that the amino group of KH-550 is only combined with the acrylic resin through hydrogen bonds, while the covalent bond of KH-570 is significantly more stable, the interface shear strength is reduced, and it is easy to delaminate during wear, and KH-550 cannot effectively disperse nano-SiO 2 , the defects at the resin-filler interface increase, which in turn leads to the increase in the size of wear debris.

[0023] Hydrophobicity and flammability test: The contact angle test was performed on the composite board samples prepared in Example 2 and Comparative Example 4. The larger the contact angle, the better the hydrophobic effect. All samples were tested at room temperature and 50% humidity. 5 μL of water droplets were used for each test. The results are shown in Table 2 below. According to the standard GB / T 8624-2012, Example 2 and Comparative Examples 1 and 4 were tested. They can be divided into A: non-combustible material; B1: flame retardant material; B2: combustible material; B3: flammable material. The results are shown in Table 2 below.

[0024] Table 2. Hydrophobicity and flammability test results of composite panels

[0025] It can be seen from the results in Table 2 that the composite board prepared by the present invention has excellent hydrophobicity and good flame retardant effect. ZnO promotes corn cob carbon to form a dense carbon layer at high temperature to isolate oxygen and heat. Magnesium oxide and magnesium sulfate synergistically decompose and absorb heat, delaying the temperature rise of the substrate layer. KH-570 copolymerizes with the resin to form a dense surface to inhibit flame penetration. The multi-level synergy effectively achieves the flame retardant effect. From the results of Comparative Example 1 and Example 2, it can be seen that ordinary carbon has no ZnO catalysis, and the loose and porous carbon layer may cause oxygen diffusion and thus intensify combustion. From the results of Comparative Example 4 and Example 2, it can be seen that KH-550 is difficult to form a stable crosslink with the resin, the protective layer is delaminated at high temperature, and the carbon layer is broken. The broken carbon layer causes oxygen to enter the substrate layer, thereby initiating secondary combustion and causing a significant decrease in flame retardancy.

[0026] Antibacterial test: fresh bacterial suspensions of Staphylococcus aureus, Escherichia coli and Candida albicans were prepared at a concentration of 1×10 8 CFU / mL, the composite board samples prepared in Example 2 and Comparative Examples 1, 2, and 4 were cut into 50×50 mm test pieces, the surface was wiped with alcohol for disinfection, and ultraviolet irradiation was treated for 30 min, then 40 μL of bacterial solution was added to the surface of the test piece, covered with a polyethylene film, and cultured for 24 h at 37°C and 90% humidity. The surviving bacteria were eluted with 10 mL of PBS buffer, and the agar plate was coated with gradient dilution. After culturing at 37°C for 24 h, the colony forming units (CFU) were counted and the antibacterial rate (%) was calculated = (1-test sample CFU / blank control CFU) × 100%, the blank control was a commercially available non-antibacterial board, and the test results were as follows Figure 3 shown.

[0027] Depend on Figure 3The results show that the composite board prepared by the present invention exerts an excellent antibacterial effect through the synergistic effect of multiple layers and multiple raw materials; from the results of comparative example 1 and example 2, it can be seen that ordinary carbon has no ZnO loading and cannot produce active oxygen. The antibacterial ability of the panel layer is only provided by nanosilver, but the inhibitory effect on fungi (Candida albicans) is significantly affected; from the results of comparative example 2 and example 2, it can be seen that the lack of the main antibacterial nanosilver has significantly affected the antibacterial effect, and the antibacterial rate has dropped sharply; from the results of comparative example 4 and example 2, it can be seen that the amino group of KH-550 may be combined with nanosilver particles, resulting in nanosilver agglomeration, a decrease in specific surface area, a decrease in silver ion release, and the synergy with the ZnO of the panel layer is affected, which leads to a certain degree of influence on the antibacterial effect.

[0028] Spectrum test: The ZnO@corncob porous carbon sample prepared in Example 2 was placed on a SEM sample tray, fixed with an adhesive carbon tape, covered with a layer of carbon by spraying, and the sample surface was scanned with an electron beam. The results are as follows: Figure 4 shown.

[0029] Depend on Figure 4 The results show that the image shows an obvious porous structure, relatively uniform pore distribution, rich micropores and mesopores, and typical characteristics of porous carbon materials; the surface is rough and the structure is fluffy, with a large specific surface area and a developed pore network, which enables effective loading and dispersion of nanoparticles.

[0030] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An agricultural waste modified composite board, characterized in that: Its components from top to bottom include: panel layer, substrate layer, weight reduction layer and protective layer; The panel layer comprises the following components by weight: 15 to 18 parts of ZnO@corncob porous carbon, 8 to 12 parts of magnesium oxide, 5 to 6 parts of magnesium sulfate, 1 to 1.2 parts of hydroxyethyl cellulose, 0.2 to 0.25 parts of silane coupling agent, 8 to 10 parts of sunflower disk carbon, 18 to 22 parts of isocyanate glue and 12 to 14 parts of light calcium carbonate, as well as a glass fiber cloth and a non-woven fiber cloth. The substrate layer comprises the following components by weight: 10 to 15 parts of sunflower stalk carbon fiber, 2 to 3 parts of nano-SiO2, 0.2 to 0.3 parts of silane coupling agent, 12 to 15 parts of hemp fiber, 6 to 8 parts of hollow glass microspheres, 0.4 to 0.5 parts of nano-silver, 0.5 to 0.6 parts of hydroxyethyl cellulose and 15 to 20 parts of isocyanate glue, and two sheets of non-woven fiber cloth; The composition of the weight-reducing layer includes the following components by weight: 15 to 20 parts of rice husk ash porous carbon, 8 to 12 parts of sunflower stem carbon powder, 12 to 15 parts of bio-modified asphalt, 0.3 to 0.5 parts of hydroxymethyl cellulose, 10 to 14 parts of short-cut basalt fibers and 12 to 15 parts of water-based polyurethane glue, and a basalt fiber mesh; The protective layer comprises the following components in parts by weight: 8 to 12 parts of ZnO@corncob porous carbon, 4 to 6 parts of sunflower disc carbon, 8 to 12 parts of polyvinyl acetate emulsion, 12 to 15 parts of polyurethane acrylate, 0.3 to 0.5 parts of hydroxymethyl cellulose, 0.5 to 0.8 parts of KH-570 silane coupling agent, 15 to 20 parts of water-based acrylic resin and 2 to 3 parts of nano-SiO2, as well as a glass fiber cloth and a basalt fiber mesh.

2. The agricultural waste modified composite board according to claim 1, characterized in that: The specific preparation steps of the ZnO@corncob porous carbon are as follows: S1: completely immersing agricultural waste corn cobs in deionized water, then immersing them in a NaOH solution, washing them with water, drying them, crushing and screening them to obtain pretreated corn cobs; S2: adding the pretreated corn cob prepared in step S1 into a reaction furnace, heating it up and then keeping it warm under a nitrogen atmosphere, and then naturally cooling it to room temperature to obtain a carbonized product; S3: mixing the carbonized product in step S2 with phosphoric acid, performing an impregnation treatment, and then drying the mixture, adding the mixture into a reaction furnace, heating the mixture under a nitrogen atmosphere, and then performing a heat preservation treatment, naturally cooling the mixture to room temperature, soaking the mixture with a sodium hydroxide solution, washing the mixture with deionized water, and drying the mixture to obtain an activated product; S4: immersing the activated product prepared in step S3 in a zinc nitrate aqueous solution, vacuum impregnating, stirring, drying, adding to a reaction furnace, heating to 600-650° C. under a nitrogen atmosphere, heat preservation, naturally cooling to room temperature, ultrasonic treatment, and drying to obtain ZnO@corncob porous carbon.

3. The agricultural waste modified composite board according to claim 2, characterized in that: In step S3, the ratio of the carbonized product to the phosphoric acid is 1 g: 0.5-1 mL; in step S4, the ratio of the activated product to the aqueous zinc nitrate solution is 1 g: 10-15 mL; and the ultrasonic treatment parameters are 100-150 W, 40 kHz, and time 20-30 min.

4. The agricultural waste modified composite board according to claim 3, characterized in that: The specific preparation steps of the bio-modified asphalt are as follows: S101: heating the asphalt to obtain preheated asphalt; drying the lignin powder to obtain pretreated lignin; mixing the preheated asphalt and the pretreated lignin, maintaining the temperature, stirring and mixing, then adding KH-570 silane coupling agent, continuing the stirring, and standing to obtain bio-modified asphalt.

5. The agricultural waste modified composite board according to claim 4, characterized in that: In step S101, the mass ratio of the preheated asphalt and the pretreated lignin is 0.7-0.8:0.2-0.3; the amount of the KH-570 silane coupling agent is 1-2% of the amount of the substrate.

6. The agricultural waste modified composite board according to claim 5, characterized in that: The specific preparation steps of the sunflower stalk carbon fiber are as follows: S201: The sunflower stalks are pressurized to separate cellulose and lignin to obtain loose fiber bundles; the loose cellulose is heated to 1200° C. in a nitrogen atmosphere, kept warm, naturally cooled to room temperature, washed with deionized water and ethanol, then soaked in a KH550 solution, and dried to obtain sunflower stalk carbon fibers.

7. The agricultural waste modified composite board according to claim 6, characterized in that: The silane coupling agent in the panel layer and the substrate layer is any one of KH-550 silane coupling agent, KH560 silane coupling agent and KH792 silane coupling agent.

8. A method for preparing the agricultural waste modified composite board according to any one of claims 1 to 7, characterized in that: The specific preparation steps are as follows: S301: Add ZnO@corncob porous carbon, magnesium oxide, magnesium sulfate, sunflower disc carbon and light calcium carbonate into a mixer according to weight, pre-mix, then add hydroxyethyl cellulose and silane coupling agent, mix; add isocyanate glue, stir to obtain panel layer slurry; evenly coat the prepared panel layer slurry on glass fiber cloth, then stick non-woven fiber cloth, place the mold in a hot press, hot press, and oven ageing to obtain the panel layer; S302: immersing hemp fiber in a silane coupling agent solution, adjusting the pH, and drying after the immersion to obtain pretreated hemp fiber; adding nanosilver to part of the isocyanate adhesive, ultrasonically treating it, adding the remaining isocyanate adhesive, stirring it, and obtaining a pretreated adhesive; adding nano-SiO2, hollow glass microspheres and sunflower stem carbon fiber into a mixer, premixing, adding hydroxyethyl cellulose, and mixing; Add pretreated adhesive, stir, add pretreated hemp fiber, stir to obtain substrate layer slurry; evenly apply the substrate layer slurry to the non-woven fiber cloth, cover with a second layer of non-woven fiber cloth, place the mold in a hot press, perform pre-pressing, pressure-raising, temperature-raising and pressure-maintaining, and oven-aging to obtain a base plate; S303: adding rice husk ash porous carbon, sunflower stem carbon powder and chopped basalt fiber into a mixer, mixing, adding hydroxymethyl cellulose, stirring, adding bio-modified asphalt and water-based polyurethane adhesive, stirring, and obtaining a weight-reducing layer coating; The weight-reducing layer coating is evenly applied to the basalt fiber grid, and the mold is placed in a hot press, subjected to pressure maintenance treatment, and then subjected to pressure reduction treatment, and allowed to stand to obtain the weight-reducing layer; S304: adding water-based acrylic resin, polyurethane acrylate, polyvinyl acetate emulsion and hydroxymethyl cellulose in sequence, mixing and stirring, then adding KH-570 silane coupling agent, stirring, adding ZnO@corncob porous carbon, sunflower flower disk carbon and nano-SiO2, stirring, and obtaining a protective layer coating; applying the protective layer coating evenly on the glass fiber cloth, covering the basalt fiber grid, and after UV curing, heat curing to obtain a protective layer; S305: stack the above-prepared layers together and arrange them in the order of protective layer, weight reduction layer, substrate layer and panel layer from bottom to top, put the stacked layers into a hot press, treat at 80°C and 1MPa pressure for 5min, increase the temperature and pressure to 120°C and 8MPa, treat for 30min, reduce the temperature and pressure to 100°C and 5MPa, treat for 20min, reduce the pressure and temperature to 50°C and 2Mpa, treat for 30-60min, cool to room temperature to obtain the formed composite sheet, cut, grind and surface treat to obtain the agricultural waste modified composite sheet.

9. A method for preparing the agricultural waste modified composite board according to claim 8, characterized in that: In step S302, the silane coupling agent solution is prepared from a silane coupling agent and a 90 wt% ethanol solution; the ultrasonic treatment parameters are 100-150 W, 40 KHz, and time 10-20 min.

10. A method for preparing the agricultural waste modified composite board according to claim 8, characterized in that: In step S304, the UV curing parameters are 365nm and the radiation intensity is 100mW / cm 2 , time 5 to 10 minutes.

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